Conventionally, in a tire mounted in a vehicle, heat generation when the tire is rolling is problematic. An increase in the temperature of the tire due to the heat generation promotes deterioration with age such as deterioration in the physical property of the tire material, and causes the breakage and the like of a tread when the vehicle travels at a high speed. Particularly, in an off-the-road radial (ORR) tire and a truck bus radial (TBR) tire to be used with a heavy load, rubber of a bead unit is deformed by friction with a rim flange and pressure from the rim flange, so that heat is easily generated. Since the heat generation in the bead unit may promote the deterioration of the rubber of the bead unit, and reduce the endurance of the tire as well as the endurance of the bead unit, a tire capable of reducing the temperature of the bead unit is required.
For example, in a tire disclosed in Patent Literature 1, as a means for reducing the temperature of the bead unit, a turbulence generating protrusion is formed along the tire radial direction over the range from a side unit to the bead unit. Accordingly, turbulence with high flow velocity is generated on the tire surface and heat dissipation in the bead unit is promoted, so that an increase in the temperature of the bead unit is suppressed.